JP3854422B2 - Electrode sensor for detecting stress corrosion cracking and stress corrosion cracking monitoring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode sensor for detecting stress corrosion cracking and a stress corrosion cracking monitoring apparatus. Stress corrosion cracking is a phenomenon in which a metal material placed in a specific corrosive environment causes time-dependent brittle cracking under a connecting tensile stress. This is a typical environmental embrittlement that cracks only when the material structure, corrosive environment, and stress satisfy certain conditions. It is a necessary condition that stress and corrosive action work simultaneously, and cracking occurs even in a much lower stress below the yield stress or in a weak corrosive environment as compared with the case of breaking by stress alone. Austenitic stainless steel-chloride aqueous solution, carbon steel-caustic aqueous solution, and brass-ammonia aqueous solution are known as specific combinations of materials / environments that cause cracking.
[0002]
[Prior art]
Since stress corrosion cracking occurs even at a very low stress as compared with the case of breaking by stress alone, it is desired to detect the stress corrosion reliably.
However, there has been no apparatus for monitoring stress corrosion cracking. Many surface corrosion monitoring sensors have been proposed so far. For example, there are sensors utilizing an electric resistance method, a polarization resistance method, an alternating current impedance method, etc., but it is impossible to monitor stress corrosion cracking.
[0003]
[Problems to be solved by the invention]
In view of the circumstances described above, an object of the present invention is to provide a stress corrosion cracking electrode sensor and a stress corrosion cracking monitoring device that can monitor stress corrosion cracking and can easily set a stress value equivalent to that of a monitoring object. .
[0004]
[Means for Solving the Problems]
The stress corrosion cracking detection sensor according to claim 1 is a cylindrical body having a hemispherical front end and a rear end sealed by a sealing block, and a collation for generating a reference potential with a working electrode filled with a pressure medium. An electrode, a holder for holding the working electrode and the reference electrode, and for attaching to the monitoring object; a pressurizing means for applying an arbitrary pressure to the pressure medium in the working electrode; and a pressure in the working electrode In order to detect the pressure fluctuation of the medium, the detection port is formed of a detection port formed in the hermetic block.
A stress corrosion cracking detection sensor according to a second aspect is the pressure screw according to the first aspect, wherein the pressurizing means is screwed into a hermetic block of the working electrode, and a tip can enter and retract into the working electrode. It is characterized by being.
According to a third aspect of the present invention, the stress corrosion cracking detection sensor according to the first aspect is characterized in that the pressurizing means is a pressurizing pump for supplying a pressure medium into the working electrode.
According to a fourth aspect of the present invention, there is provided a stress corrosion cracking monitoring apparatus comprising: a pressure sensor connected to the detection port of the electrode sensor for detecting stress corrosion cracking according to the first aspect; Is connected.
[0005]
According to the invention of claim 1, when the holder is attached to the monitoring object and an arbitrary pressure is applied to the pressure medium in the working electrode by the pressurizing means to create a pressure condition similar to that of the monitoring object, the working electrode By monitoring the potential difference between the reference electrode and the reference electrode, the potential oscillation peculiar to stress corrosion cracking can be observed. For this reason, the stress corrosion cracking of the object can be monitored.
According to the invention of claim 2, since the load pressure to the pressure medium in the working electrode can be arbitrarily set by adjusting the screwing amount of the pressure screw, stress corrosion cracking of various objects can be monitored, And it can be done easily by hand.
According to the invention of claim 3, since the load pressure to the pressure medium in the working electrode can be arbitrarily set by the pressurizing pump, the stress corrosion cracking of various objects can be monitored, and the operation can be automatically performed.
According to the invention of claim 4, the pressure setting in the working electrode can be monitored by the pressure sensor, and the potential difference between the working electrode and the reference electrode can be detected by the corrosion potential measuring device. Can be monitored, thereby ensuring that stress corrosion cracking can be monitored.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
1 is a cross-sectional view of an electrode sensor for detecting stress corrosion cracking according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing another example of a working electrode, and FIG. 3 is an explanatory view showing another example of a pressurizing means. FIG. 4 is an explanatory diagram of a use state of the stress corrosion cracking monitoring apparatus according to one embodiment of the present invention.
[0007]
In FIG. 1, 1 is a holder, and a flange portion 1b is formed at the upper end of the body portion 1a. An appropriate number of bolt holes 1c are formed in the flange portion 1b so that the mounting bolts 11 can be passed therethrough. The holder 1 is preferably made of a synthetic resin such as a fluororesin or a vinyl chloride resin in order to provide electrical insulation.
[0008]
A working electrode 2 is attached to the center of the holder 1. This working electrode 2 is a thin-walled cylindrical body, its tip end portion 2a is formed in a hemispherical shape, and a boss member 3 is attached and sealed at its base end. The distal end portion 2 a is exposed on the lower surface of the holder 1.
The tip 2a of the working electrode 2 is formed in a hemispherical shape in order to generate a uniform stress at the tip. The working electrode 2 is made of the same material as that of the monitoring object, for example, SUS material.
Further, the gap between the working electrode 2 and the holder 1 is filled with a filler 12 such as epoxy resin or silicon sealant so that no gap is generated. By doing so, as described later, when the pressure medium in the working electrode 2 is pressurized, there is no gap between the holder 1 and the working electrode 2, so there is no inconvenience in monitoring.
[0009]
The boss member 3 is made of the same material as the working electrode 2, for example, SUS material. The boss member 3 is formed with a female screw hole 3a, and a pressure screw 4 is screwed therein. The pressure screw 4 is formed with a groove 4a in which a tool such as a screwdriver is fitted in the head. When the screwdriver is inserted into the groove 4a and turned by hand, the pressure screw 4 can be screwed. The tip of the pressure screw 4 can be moved into the working electrode 2 or moved backward by the advance operation. Since the working electrode 2 is filled with pure water or oil if permitted in the use environment as the pressure medium 13, when the pressurizing screw 4 enters the working electrode 2, the inside of the working electrode 2 is filled. When the pressure increases and the pressure screw 4 is retracted from the working electrode 2, the internal pressure in the working electrode 2 decreases.
[0010]
The boss member 3 is formed with a small-diameter liquid passage 5 so as to communicate from the inside of the working electrode 2 to the outside. Port 6 is formed. A set screw 7 for connecting a lead wire is screwed at an appropriate position of the boss member 3.
[0011]
Further, the holder 1 has a verification electrode 8 incorporated therein. The reference electrode 8 generates a reference potential, and a silver-silver chloride electrode or a zinc electrode is used. The tip of the verification electrode 8 faces the lower surface of the holder 1 and comes into contact with the liquid in the monitoring object.
A lead wire 9 is connected to the verification electrode 8. Further, the gap between the verification electrode 8 and the holder 1 is also filled with a filler 12 such as an epoxy resin or a silicone sealant, thereby filling the gap.
[0012]
The tensile stress σ generated on the electrode surface of the working electrode 2 can be obtained by the following formula.
σ = P · a / 2h (wherein P is the load pressure, a is the inner diameter of the working electrode 2, and h is the thickness of the tip 2a of the working electrode 2).
When the necessary generated stress is large and the load pressure is large, as shown in FIG. 2, the thickness of the tip 2a may be made thinner than the thickness of the cylinder.
[0013]
As the pressurizing means, in addition to the pressurizing screw, as shown in FIG. 3, a pressure medium is automatically injected into and discharged from the working electrode 2 by a plunger pump 14 or the like, and the pressure in the working electrode 2 is arbitrarily set. You may adjust. The pressurizing pump as the pressurizing means is not limited to the plunger pump, but the plunger pump is preferable because the pressurizing pressure is high.
[0014]
FIG. 4 shows a state in which the monitor device A incorporating the electrode sensor 10 is attached to a pipe B which is an object to be monitored.
Although the attachment method is arbitrary, in the illustrated example, the electrode sensor 10 is inserted into the attachment casing 21 of the pipe B, and the flanges are fastened with bolts.
A pressure sensor 15 is connected to the detection port 6, and a corrosion potential measuring device 16 is connected to the working electrode 2 and the verification electrode 8 via a lead wire 9.
Pipe B, which is a monitoring object, is in an aqueous solution corrosive environment due to liquid flowing through the pipe. The stress loaded in the pipe B is estimated in advance, and the working electrode 2 is caused to generate a stress equivalent to the stress. This stress is generated using the pressure screw 4 and the plunger pump 14, and it can be confirmed by the pressure sensor 15 whether the set pressure has been reached.
In this state, the monitoring system is entered, and the potential difference between the working electrode 2 and the verification electrode 8 is monitored by the corrosion potential measuring device 13.
As a result, the occurrence of stress corrosion cracking can be detected if the potential difference is a corrosion potential oscillation phenomenon peculiar to stress corrosion cracking.
[0015]
【The invention's effect】
According to the first aspect of the present invention, when the holder is attached to the monitoring object, and the same pressure condition as that of the monitoring object is created in the pressure medium in the working electrode, the potential difference between the working electrode and the reference electrode is monitored. Potential vibrations specific to corrosion cracking can be observed, and stress corrosion cracking of objects can be monitored.
According to the invention of claim 2, by adjusting the screwing amount of the pressure screw, the load pressure to the pressure medium in the working electrode can be arbitrarily set, and this can be easily done manually.
According to the invention of claim 3, the pressure applied to the pressure medium in the working electrode can be arbitrarily set by the pressurizing pump, and the operation can be automatically performed.
According to the invention of claim 4, the pressure setting in the working electrode can be monitored by the pressure sensor, and the potential difference between the working electrode and the reference electrode can be detected by the corrosion potential measuring device. Can be monitored, thereby monitoring stress corrosion cracking.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an electrode sensor for detecting stress corrosion cracking according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing another example of a working electrode.
FIG. 3 is an explanatory view showing another example of the pressurizing means.
FIG. 4 is an explanatory diagram of a usage state of the stress corrosion cracking monitoring apparatus according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Holder 2 Working electrode 3 Boss member 4 Pressure screw 6 Detection port 8 Reference electrode 10 Electrode sensor 15 Pressure sensor 16 Corrosion potential measuring device

Claims (4)

A working electrode whose tip is hemispherical and whose rear end is sealed with a sealing block, the inside of which is filled with a pressure medium;
A reference electrode for generating a reference potential;
A holder for holding the working electrode and the reference electrode and for attaching to the monitoring object;
Pressurizing means for applying an arbitrary pressure to the pressure medium in the working electrode;
An electrode sensor for detecting stress corrosion cracking, comprising: a detection port formed in the hermetic block for detecting pressure fluctuations of the pressure medium in the working electrode. 2. The electrode sensor for detecting stress corrosion cracks according to claim 1, wherein the pressurizing means is a pressurizing screw screwed into a hermetically sealed block of the working electrode and having a tip capable of entering and retracting into the working electrode. . 2. The electrode sensor for detecting stress corrosion cracking according to claim 1, wherein the pressurizing means is a pressurizing pump for supplying a pressure medium into the working electrode. 2. A stress corrosion cracking characterized in that a pressure sensor is connected to the detection port in the electrode sensor for stress corrosion cracking detection according to claim 1, and a corrosion potential measuring device is connected to the working electrode and the reference electrode via a lead wire. Monitor device.

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